Biodiversity and Conservation — BIOLOGY STD 12 Science — Question

Read the following and answer any four questions from (i) to (v) given below:

Alcohols are important industrial solvents. Ethanol, methanol, propanol and butanol are produced commercially by fermentation activity of some fungi, majorly yeasts. During fermentation, yeast cells convert cereal derived sugars into ethanol and CO₂ At the same time hundreds of secondary metabolites that influence the aroma and taste of alcohol are produced. Sugar concentration affects the rate of fermentation reactions. Yeast cannot grow in very strong sugar solution. In case of complex carbohydrate containing nutrient media, 1% malt or Rhizopus is used along with yeasts. Hydrolysis of starch is carried out at high temperature for 30 ruins. 'Tile crushed food mixed with hot water for obtaining malt in called mash. 'Tile nutrient medium prior to fermentation in called wort. Wort is cooled down to appropriate temperature and inoculated with strain of yeast.

1. Tile rate of alcohol production is measured on the basis of:

1. Amount of sugar present in the medium.
2. Amount of CO₂ produced per unit time.
3. Amount of yeast added in the medium.
4. All of these.

2. A number of chemicals are produced at the time of alcoholic fermentation with the change of nutrient media, pH and aeration. Select such by-product from the following.

1. Phenylethanol.
2. Amyl alcohol.
3. Glycerol.
4. All of these.

3. During alcoholic fermentation of cereals and potato, the crushed food mixed with hot water for obtaining malt is called:

1. Juice.
2. Mash.
3. Wort.
4. None of these.

4. Distilled alcohol with 95% ethanol content is called:

1. Absolute alcohol.
2. Rectified spirit.
3. Gin.
4. Brandy.

5. Assertion: Rhizopus or 1% malt is used in the nutrient medium when it contains complex carbohydrates.

Reason: Yeast does not possess sufficient diastase or amylase. 

1. Both assertion and reason are true and reason is the correct explanation of assertion.
2. Both assertion and reason are true but reason is not the correct explanation of assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

Read the following and answer any four questions from (i) to (v) given below:

Oogenesis is the process of formation of ovum in ovaries. It consists of three phases : multiplication, growth and maturation. Oogenesis is controlled by hormones GnRH, LH, FSH. GnRH secreted by the hypothalamus stimulates the anterior lobe of pituitary gland to secrete LH and FSH.

1. What is the function of hormone FSH?

1. It inhibits the formation of estrogen.
2. It induces the release of secondary oocyte.
3. It stimulates the growth of Graafian follicles.
4. It causes ovulation.

2. Which hormone induces the rupture of the mature Graafian follicle?

1. Follicle stimulating hormone.
2. Gonadotropin releasing hormone.
3. Progesterone.
4. Luteinising hormone.

3. Which cell division is involved in the formation of secondary oocyte?

1. Mitosis.
2. Meiosis I.
3. Amitosis.
4. Meiosis II.

4. Identify the function(s) of LH.

1. Release of secondary oocyte from Graafian follicle.
2. Stimulates corpus luteum to secrete progesterone.
3. Stimulates estrogen formation.
4. Promotes development of egg to form secondary oocyte.

1. (A) and (B) only.
2. (B) and (C) only.
3. (A), (C) and (D) only.
4. (B) only.

5. Assertion: The increase in progesterone level exerts positive feedback on GnRH.

Reason: The rising level of progesterone stimulate production of FSH and LH.

1. Both assertion and reason are true, and reason is the correct explanation of assertion.
2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
3. Assertion is true, but reason is false.
4. Both assertion and reason are false.

Explain with diagram - Hershey and Chase experiment.###On the basis of experimental proof explain the diagram that DNA is genetic material.###How did Hershey and Chase differentiate between DNA and protein in their experiment while proving that DNA is the genetic material?

Read the following and answer any four questions from (i) to (v) given below:
Many adaptations are found in flowers to achieve certain kind of pollination. The pollination achieved by insects is known as entomophily. The given diagram shows the cross-section of an anther of an insect pollinated flower.

1. Which of the following is/ are the function(s) of structure Y?

1. To carry waste products away from the anther.
2. To supply oxygen to the cells of the anther.
3. To transport food and mineral salts to the anther.
4. To supply water to the anther.

1. Conly.
2. C and D only.
3. A, B and D only.
4. A, B, C and D.

2. Which of the following most accurately describes the structures found in compartment X?

1. They contain two haploid nuclei resulting from meiosis.
2. They contain two haploid nuclei resulting from mitosis.
3. They contain two haploid male gametes, resulting from mitosis.
4. They contain a vegetative nucleus and pollen tube nucleus.

3. Which of the following is a distinctive characteristic of insect-pollinated flower?

1. All of them have nectar guides on their flowers.
2. They produce sugary fruit.
3. Their pollen grains tend to have rough surfaces.
4. They produce abundant quantities of pollen to make up for pollen grains that might be removed by the wind.

4. Which of the following are likely characteristics of the structures found in X and stamens of this plant?

S. No	Structure of X	Stamens
(a)	Abundant and light	Pendulous
(b)	Rough surfaces	Non-pendulous
(c)	Light and sticky	Pendulous
(d)	Coarse and sticky	Protrude outside the flower

5. Spiny or sticky pollen grains and large, attractively coloured flowers are associated with:

1. Hydrophily.
2. Entomophily.
3. Ornithophily.
4. Anemophily.

Explain Competition as a population Interaction with suitable examples.

Explain different types of RNA along with process of transcription.

Read the following text carefully and answer the questions that follow:
A healthy immune system defends the body against disease and infection. But if the immune system malfunctions, it mistakenly attacks healthy cells, tissues, and organs. Called autoimmune disease, these attacks can affect any part of the body, weakening bodily function and even turning life-threatening.

i. Why are autoimmune diseases called degenerative diseases? (1)
ii. Name the autoimmune disease of body muscles. (1)
iii. Which types of immunity is provided by T-lymphocytes? (2)
OR
Which immune cells form humoral immune system? (2)

Microbes are useful in household products. Explain this with suitable examples

Read the following and answer any four questions from (i) to (v) given below:

X and Y are communicable diseases, whereas Wand Z are non-communicable diseases.X is transmitted through vectors whereas Y is transmitted through droplet infection. Wis caused due to a hormone deficiency, whereas Z is a degenerative disease. Based on the above information, answer the following questions.

1. Identify W, X, Y and Z.

	W	X	Y	Z
(a)	Coronary artery disease	Cholera	Chikungunya	Chikungunya
(b)	Diabetes	Malaria	Rhinitis	Alzheimer's disease
(c)	Alzheimer's disease	AIDS	Shigella	Plague
(d)	Gonorrhea	Diphtheria	Pertussis	Anthrax

2. Select the correct statement.

1. If X is sleeping sickness then its vector is Leishrnania.
2. If Y is diphtheria then it is caused by Bacillus anthracis.
3. If W is hypothyroidism then it is caused by deficiency of thyroxine hormone.
4. If Z is myocardial infarction then patient develops acute rheumatic fever, joint pain and throat infection.

3. If X and Y both are usual diseases then which of the following holds true?

1. X could be dengue caused by flavivirus and Y could be AIDS caused by HIV.
2. X could be chikungunya whereas Y could be rhinitis.
3. X could be hepatitis whereas Y could be rabies.
4. X could be chicken pox caused by Va rice/la zoster virus whereas Y could be yellow fever caused by flavivirus

4. If X and Y both are bacterial diseases then select the correct match from the following.

1. X- Bubonic plague-Yersinia pestis
2. Y-Leprosy- Mycobacteriurn leprae
3. X-Whooping cough-Bordetella pertussis
4. Y-Botulism-Clostridiurn botulinum

5. Assertion: Communicable diseases could be contagious or non-contagious.

Reason: Diseases that spread through vectors are non-contagious disease.

1. Both assertion and reason are true, and reason is the correct explanation of assertion.
2. Both assertion and reason are true, but reason is not the correct explanation of assertion.
3. Assertion is true, but reason is false.
4. Both assertion and reason are false.

Read the following text carefully and answer the questions that follow:
When a microorganism invades a host, a definite sequence of events usually occur leading to infection and disease, causing suffering to the host. This process is called pathogenesis. Once a microorganism overcomes the defense system of the host, development of the disease follows a certain sequence of events as shown in the graph. Study the graph given below for the sequence of events leading to appearance of a disease and answer the questions that follow:

i. In which period, according to the graph there are maximum chances of a person transmitting a disease/infection and why? (1)
ii. Study the graph and write what is an incubation period. Name a sexually transmitted disease that can be easily transmitted during this period. Name the specific type of lymphocytes that are attacked by the pathogen of this disease. (1)
iii. Draw a schematic labelled diagram of an antibody. (2)
OR
In which period, the number of immune cells forming antibodies will be the highest in a person suffering from pneumonia?
Name the immune cells that produce antibodies. (2)